Specialized monocoque construction for radar indicators



F. M. KRANTZ ETAL 2,839,344

SPECIALIZED MONOCOQUE CONSTRUCTION FOR RADAR INDICATORS Filed May 9, 1956 June 17, 19 58 3 Sheets-Sheet 2 INVENTORS A ORNEY5 n 1958 F. M. KRANTZ ETAL 2,339,344

SPECIALIZED MONOCOQUE CONSTRUCTION FOR RADAR INDICATORS Fild ma 9, 1956 s Sheets-Sheet :5 a

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A ORNEY5 United States Patent "ice SPECIALIZED MONOCOQUE CONSTRUCTION FOR RADAR INDICATORS Frank M. Krantz, Ellicott City, and Richard F. Huelskamp, Baltimore, Md., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application May 9, 1956, Serial No. 583,890

4 Claims. (Cl. 312-4) This invention relates to cabinets or cases for housing electronic equipment and more particularly to cases for housing radar indicators and component equipment. Essentially there are two ways possible to fabricate an indicator case, The first method is to build up a frame and wrap a cover around it. The second is to fabricate the case entirely of sheet metal, welded and formed to produce a case with only minor frame reinforcements. Both of these methods have inherent disadvantages. The framed structure is likely to become too heavy for light-weight, portable equipment. The folded sheet case, while light in weight, has poor accessibility due to the fact that designers have had to limit the number of openings to maintain case strength. In addition, the folded case is susceptible to fracture under severe shock, particularly near the openings where welds have been made. Various compromises have been used combining the frame and folded sheet techniques with varying degrees of success.

An object of this invention is to provide an indicator case of decreased weight to volume ratio for a given indicator.

Another object of this invention is to provide, in an indicator case, increased accessibility to all electronic components without the use of slides, swinging chassis, or other weight-increasing structures.

Another object of this invention is to provide an indicator case having favorable shock characteristics.

A still further object of this invention is to provide an indicator case of simple design resulting in relatively low fabrication costs.

In accordance with this invention, there is provided a specialized type of monocoque construction which yields both minimum weight and highly accessible units while maintaining an excellent resistance to shock damage.

A true monocoque design, by definition, would be a structure in which the entire load stress is carried in the outer paneling or skin, no internal frame being present. This design has beep successfully applied to aircraft. It is the best light-weight design obtainable, involving a minimum of construction details. However, true monocoque construction provides only limited accessibility within the structure. This follows from the fact that in order to maintain skin strength the openings in the case must be kept to a minimum. The present invention provides a means of compromising the monocoqueprinciple to allow maximum accessibility, commensurate with the lightweight features obtainable with this type of design.

The above and other objects and advantages of the invention will hereinafter become more apparent from the following description and accompanying drawings, which illustrate a preferred embodiment, and wherein:

Fig. 1 is a side elevation view of a radar indicator case in accordance with this invention with parts broken away to show the mounting of a cathode ray tube;

Fig. 2 is a side elevational view, to a slightly smaller scale, showing an interior frame and skin assembly, as viewed from the right of Figs. 3 and 4;

2,839,344 Patented June 17, 1958 Fig. 3 is a top plan view of the welded frame and skin assembly inaccordance with this invention;

Fig. 4 is a front elevational view of the welded frame and skin assembly shown in Fig. 3;

Fig. 5 is a horizontal sectional view taken on line 5--5 of Fig. 1; and Fig. 6 is a partial perspective of the welded frame assembly in accordance with this invention.

Referring now to the drawings, first to Fig. 6, a basic frame, indicated generally by numeral 10, includes a rear rectangular frame 12 and a forwardly projecting U-shaped frame 14. The frame 12 is formed of tubing, rectangular in cross section, and includes a pair of uprights 16 and 17 connected by a pair of horizontal members 18 and 19, which upright and horizontal members are welded into a unitary structure. The U-shaped frame 14, which also is tubular, rectangular in cross section and somewhat larger in cross section, comprises two uprights 20 and 21, and a horizontal member 22, with the horizontal member welded to the lower portions of the uprights to form a unitarystructure. As shown in Fig. 6, the top of the rear upright 21 is arranged in abutting relation with the under surface of the top horizontal member 18 at the mid-portion thereof and the two members are welded into a unitary structure at this juncture.

shaped in top plan, are attached, as by blind aircraft type rivets 26 (Figs. 2 and 4), to the front face of the rectangular frame 12 and the side faces of the U-shaped frame 14. As shown in Fig. 4, the rear or short leg of each of the panels 24 and 25 extends from bottom to top of the rectangular frame 12, whereas, as shown in Fig. 2, the long legs of the panels 24 and 25 extend from the bottom to a point substantially midway the top and bottom of the U-shaped frame member 14. Also as shown in Fig. 2, the long legs of each of the inner panels 24 and 25 are cut away into substantially U-shape at the top thereof. The interior panels 24 and 25 provide component mounting areas and bracing stiffness to the structural frame 10.

In addition to these functions, the panels 24 and 25 divide the lower half of the assembled case into two corn partments A and B, whereas, the upper half of the case is utilized as a single compartment C, each to be referred to hereinafter.

As shown in Fig. 5, a U-shaped strap 28 extends along the sides and front of the case at the lower portion thereof.

This strap is welded at each end of the U to the lower portion of each of the uprights of the rear rectangular frame Each of the exterior panels is provided with folded stiffening edges on four sides thereof, by which they are attached to the frame and to each other, as by quick-acting fasteners.

The bottom panel or base member 40 is first attached to the frame by means of screws 42 (Fig. 1). Then the top panel 38 is attached to the frame by means of a At the bottom, the rear upright 21. is notched so as to fit in abutting relation with the top and front midpair of brackets 41 attached to the top portion of the uprights 16 and 17 of the rear frame member and a bracket 41' attached to the upper portion of from upright 20 of the U-shaped frame member. As shown in Fig. l, the brackets 41 and 41 are attached to the frame members by fasteners 43 and the top panel is attached to the brackets by fasteners 44. The rear exterior panel 30 is then attached to the rear surface of the rectangular frame by fasteners 45, Figs. 1 and 5. Then the side panels 34 and 36 are attached to the U-shaped strap and to the rear panel by fasteners 46. And lastly, the front exterior panel 32 'is attached to the front top and bottom corners of the side panels by fasteners 48. For minor servicing of the unit the front panel may be removed independently. For clear all around access the side panels may also be removed. This allows three-sided approach to the electronic components unhampered by corner posts.

The electronic components, only a few of which are shown, will, of course, have been mounted on the interior panels before the outer panels have been attached. Heavy components, such as transformers, large capacitors, magnetic amplifiers and the like are attached directly to the inner panels 24 and 25. Smaller components, such as electron tubes, printed circuits and the like, may be attached to sub-chassis which are mounted on the interior panels.

By way of illustration, there is shown in Fig. 1, a means of mounting a cathode ray tube D in the upper compartment C of the case. This mounting comprises a platform 50, only one side of which is shown, pivotally mounted at each side of the rear thereof by a bolt 52 carried by a bracket 54, which bracket is attached by bolts 56 to the rear of the basic frame. At the front, the platform is adjustably supported from a cross member 58 by a bolt 6t). Extending upwardly from the platform and welded thereto is a pair of cradle members 62, which cradle members are shaped to receive the tube D and are anchored at the top by suitable means, not shown. Suitable cushions 64 are located between the cradle members and the cathode ray tube. is provided with the usual opening, not shown, in the face thereof for viewing the tube.

In Figs. 1 and 5, there are shown by way of example, two heavy components E and F mounted within compartments A and B, respectively, and two sub-chassis G and H. The heavy components are supported by the basic frame members and by the interior panels 24- and 25. The sub-chassis G and H, which carry small components, such as electron tubes, printed circuits and the like, are movably mounted within the compartments A and B, respectively, by suitable means, not shown. These components and sub-chassis are attached to the component mounting areas by anchor nuts (not shown) riveted to these areas.

With reference to Fig. 5, it is seen that compartments A and B are thermally insulated from each other by the interior panels 24 and 25 and by a quiet air space 1 therebetween. With this arrangement, the heat sensitive elements, which may all be located in one compartment, say compartment A, are isolated from the heat producing elements which may all be located in compartment B. Thus the use of transistors is made more feasible. As shown, in Fig. l, the front face of the base or supporting panel 40 is set back relative to the front panel 32,

' thus providing a toe space and an opening for the entrance of cooling air, which air after passing upward through compartments A, B and C may be discharged through louvers, not shown, in the upper portion of the rear-panel.

The top panel 38 Without further description, it will thus be seen, in accordance with this invention there is provided a specialized type of monocoque construction which yields both minimum weight and highly accessible units while maintaining an excellent resistance to shock damage and an isolating of heat sensitive elements from heat producing elements, and while a single embodiment of the inven tion has been illustrated and described herein, the invention obviously may take other forms and be variously applied without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

l. A vertical casing for a radar indicator comprising a vertical unitary frame T-shaped in top plan and U- shaped in side elevation, said frame being formed of tubular members rectangular in cross section, interior panel members mounted on said frame and adapted to mount components of said radar indicator, said interior panel members each being formed of a single sheet L- shaped in top plan and being mounted on opposite sides of the stem of the T-shaped frame, and radially removable exterior panels enclosing said frame and interior panels on all sides thereof.

2. A vertical casing for a radar indicator comprising a unitary frame including a vertical rectangular frame member and a vertical U-shaped frame member, said latter frame member having one leg thereof intersecting said rectangular frame substantially midway its width and forming a column for said rectangular frame, each of said frame members being formed of tubular members rectangular in cross section, a pair of interior panel members L-shaped in top plan arranged one on each side of said U-sl1aped frame member and forming therewith a structure substantially T-shaped in top plan, means on said interior panels for mounting indicator components thereon, and readily removable exterior panel members mounted on said structure and forming outer walls of said casing.

3. A rectangular casing for electronic equipment comprising a unitary frame structure including a first vertical frame member of substantially the same contour as a rear wall of said casing and located immediately adjacent the interior of such rear wall, a second vertical frame member of substantiallythe same contour as opposite side walls of said casing, each of said frame members being formed of tubular members rectangular in cross section, said second frame member intersecting said first frame member intermediate its length and forming therewith a pair of spaces each entirely open at one corner and two intersecting sides, and exterior panel members removably mounted on said frame structure for closing said intersecting sides.

4. A rectangular casing as set forth in claim 3 which includes a pair of interior panel members substantially L-shaped in top plan, means mounting said panels on opposite sides of said second frame member with one leg of each of said panels extending in opposite directions from said second frame member in parallel relating to said first frame member and with the other leg of each of said panels extending in the same direction on opposite sides of said second frame member and in spaced relation to each other to thereby isolate said pair of spaces from each other.

References Cited in the tile of this patent UNITED STATES PATENTS 2,480,568 Garvin Aug. 30, 1949 2,543,146 Bace Feb. 27, i. 2,598,957 Wolfe June 3, 1952 2,691,562 West Oct. 12, 1954 

